As is well-known, a solid titanium based catalyst component with magnesium, titanium, halogens, and electron donors as basic ingredients can be used in olefin polymerization, in particular in polymerization of α-olefins having three or more carbon atoms, to produce polymers with a high yield and of high stereoregularity. Electron donor compounds are a necessary ingredient of the catalyst component. With development of internal electron donor compounds, catalysts for olefin polymerization are continuously upgraded. Currently, a plurality of electron donor compounds have been disclosed, such as polycarboxylic acids, monocarboxylic esters or polycarboxylic esters, anhydrides, ketones, monoethers or polyethers, alcohols, amines, and derivatives thereof.
In the prior art, there is citation of a diol diester compound, which, when serving as an electron donor, enables a catalyst with excellent comprehensive performance in olefin polymerization. When the catalyst is used in propylene polymerization, it presents high polymerization activity and stereoselectivity, producing polymers with wide molecular weight distribution. However, the activity, hydrogen response, or stereoselectivity of the catalyst are not really satisfactory, especially in producing polymers of high melt indexes in the presence of highly concentrated hydrogen, wherein isotactic indexes of the polymers obtained are still to be improved.
The present disclosure provides a catalyst component and a catalyst, using a diol diester as an internal electron donor compound, wherein said diol diester is obtained by reacting a non-end group diol having more than 6 carbon atoms in the straight chain with benzoic acid having at least one hydrocarbyl, i.e., Cm (m≧2) substituted group. The catalyst of the present disclosure has a high polymerization activity and hydrogen response. When the catalyst of the present disclosure is used in olefin polymerization, especially propylene polymerization, polymers with higher isotacticity or a higher melt index can be obtained.